A conventional apparatus for referring to a content of a dial memory in a telephone set comprises a dial memory group, each dial memory storing subscriber's data such as a telephone number, a name corresponding to the telephone number, etc., a key input unit for generating a reference signal for referring to the content of the dial memory, and a CPU including a whole memory reference means for referring in turn to the contents of the dial memory group in accordance with the reference signal supplied from the key input unit.
In operation, it is assumed that a forward direction reference key is pressed by an operator, so that a reference signal for the instruction of referring in the forward direction to the contents of the dial memory group is supplied from the key input unit to the CPU. As a result, a content of a starting dial memory is referred to and displayed on a display by the whole memory reference means. When the forward direction reference key is again pressed by the operator for the second time, a content of a dial memory which is positioned next in alphabetical order to the starting dial memory is referred to be displayed on the display by the whole memory reference means. In this manner, the dial memory group is referred in the forward direction as a result of pressing the forward direction reference key a predetermined number of times, until a dial memory storing a telephone number of a person that the operator wants to know is referred to and displayed on the display. Consequently, a predetermined telephone number is obtained for the operator. If a reverse direction reference key is pressed on by the operator, the dial memory group is referred in the reverse direction of the alphabetical order, until a predetermined telephone number is displayed on the display.
However, the conventional apparatus for referring to a content of a dial memory in a telephone set has a disadvantage in that it takes a long time to obtain the predetermined telephone number, because the whole contents of the dial memory group are referred in the forward or reverse direction of the alphabetical order as instructed by the operator until the predetermined telephone number is displayed. As the number of telephone numbers which are stored in the dial memory group increases the time in which the predetermined telephone number is referred is further increased.